The present invention generally relates to apparatuses for stopping rotation of tape reels, and more particularly to an apparatus capable of rapidly and positively stopping the rotations of a first and second tape reels which are driven independently, without introducing slack or damages to a recording medium of a tape form wound by these first and second tape reels, by use of digital signals.
In an apparatus which winds a recording medium of a tape form (hereinafter simply referred to as a tape) from one tape reel which feeds the tape to another tape reel which takes up the tape, as in a magnetic recording and/or reproducing apparatus (tape recorders, VTRs, electronic calculators, and the like), the rotation of the tape reels must be stopped rapidly without introducing slack or damage in the tape, when changing from an operational mode such as a fast-forward or rewind mode to a stop mode. Conventionally, as a general method for stopping the rotation of a motor, there are known methods such as: (1) a mechanical stopping method which uses a mechanical brake and the like, and (2) an electrical method which obtains stopping torque by shortcircuiting the motor terminals, a method which applies reverse torque to the tape reel driving motor by applying a reverse voltage, and the like. However, in the above mechanical stopping method, a braking mechanism which is a separate system, becomes unnecessary, and there was a limit in reducing the size of the reproducing apparatus. Accordingly, when the above braking mechanism is used frequently, degradation is introduced in the reliability of the system due to break down of the system and the like. Moreover, the mechanical noise generated by the solenoid which drives the above brake is large. On the other hand, in the above electrical stopping method, sufficient stopping torque could not be obtained by use of the method which short-circuits the motor terminals. Further, there was a disadvantage in that control was difficult to perform in the method which applies a reverse voltage to the motor.
The method which applies the above reverse voltage to the tape reel driving motor is capable of stopping the rotation of the motor more rapidly than the method which short-circuits the motor terminals. However, in the electrical method which applies the reverse voltage, detection must be performed to detect the stoppage of rotation of the tape reel or the tape reel driving motor, in order to interrupt the application of the reverse voltage. As a method of detecting the stoppage of rotation of the tape reel or the tape reel driving motor, there is a method which detects the stoppage of rotation by an output pulse of a pulse generator by use of a combination of a magnet and a detection head, a photoelectric element, or a contact switch and the like, for example, However, the accuracy in detecting the stoppage of rotation was relatively low. Furthermore, when attempting to increase the accuracy of the detecting operation, the construction of the apparatus becomes complex, and the cost of the apparatus increases.
Therefore, the realization of an apparatus for stopping rotation of tape reels of a simple construction and low cost was highly desired, which is capable of rapidly and positively stopping the rotation of the tape reels without introducing slack or damage in the recording medium of a tape form.